A′

A

7

Figure 8 12A,

13

9, 11A

11B

10

12B, 15

12C

Figure 14

Hc1

Hc1

Hc1

HNt

HNt

Hc1

HNt

AHc2

HNch1

AHct

HNb1

HNb2

AHc2

AHf2

AHc2

AHc2

He

AHc2

HNb2

HNb2

Nm

AHc2

AHc2

HNb2

AHc2

HNch2

AHc2

AHc2

AHc2

AHc2

Nm

Nm

HNb2

HNb2

AHc2

AHf2

Nm

HNb2

AHf2

HNch1

AHc2

Nm

AHc2

Nm

Nm

HNt

HNb2

HNb2

Nm

HNt

HNt

HNt

HNch1 HNch2

Nm

HNt

Nm

HNt

HNch1

AHc2

HNt

Nm

HNb2

Nm

Nm

Nm

HNb2

HNb2

AHc2

AHc2

Hb3

HNb2

AHc2

HNb1

Hh

Hl

AHf2

Hb3

HNb2

He

HNb2

Hl

HNt

Hb3

He

Hl

AHc2

Hb3

Nm

HNb1

Hl

Hc1

AHc2

Ad

AHf2

AHc2

Hf1

HNb2

AHc2

AHc2

HNb2

HNch2

Hh

AHc2

Hl

Nm

Nm

AHc2

AHf2

Nm

Hb3

Nm

HNb2

AHc2 HNb2

AHf2

AHc2

AHc2

AHf2

AHc2

Nm

HNb2

Nm

HNb2

Hc1

HNb2

AHf2

HNb2

Nm

Nm

Nm

Morava Valles

MARGARITIFER

TERRA

Lorica Polotsk

Longa

Glazov

Campos

Manzī

Echt

Bend

Gori

Bogra

Revda

Boru

Globe Ely

Cluny

Alga

Chekalin

Balta

Thule

Circle Kirsanov

Calbe

NOACHIS

TERRA

Cobalt

Ōmura

Inta Irbit

Lar

Sandila

Buta

Eberswalde

Bigbee

Holden

Nardo Uzboi Vallis

Erythraea Fossa

Tak

Jal

Bison

Ostrov

Kaj Livny

Haraḑ

L a d o

n

Va l l e

s

325°E 335°E

330°E 331°E 332°E 333°E 334°E 335°E

328°E 329°E 330°E 327°E 326°E

325°E 326°E 327°E 328°E 329°E

331°E 332°E 333°E 334°E

13°S

14°S

15°S

17°S

18°S

16°S

19°S

20°S

21°S

22°S

23°S

24°S

25°S

26°S

27°S

28°S 28°S

27°S

26°S

25°S

24°S

23°S

13°S

14°S

15°S

16°W

17°S

18°S

19°S

20°S

21°S

22°S

U U

U

U

U

AMAZONIAN

Late

Early

Middle

Floor fracturing

End of fan activity

Layered materials

Uzboi-Holden flood

Uzboi-Ladon-Morava flooding

Crater degradation

Holden crater impact

Holden basin impact

Middle Ladon basin impact

Late

Early

Late

HESPERIAN NOACHIAN PERIOD

EPOCH

SURFICIAL

N(2) DEPOSITS

PLATEAU AND

HIGHLAND UNITS

MAJOR

EVENTS

CORRELATION OF MAP UNITS

[U, unconformity between unit and superimposed units]

CRATER

UNITS

SEVERELY

DEFORMED

UNITS

BASIN, CRATER, AND

CHANNEL-FILL UNITS

10

100

1,000

10,000

? ?

Ad

AHc2

Hc1

AHct

AHf2

Hl

He

Hf1 Hh

Hb3

HNb2

HNb1

HNch1 HNch2

HNt

Nm

14

Dune unit (Late Amazonian)—Concentration of typically dark-toned bedforms. 

Type locality: Holden crater floor at lat 25.65° S., long 33.5° W. 

(CTX image P16_007125_1530_XN_27S033W)

At type locality, size of barchan dunes increases and spacing decreases 

from north to south. Subjacent Hesperian Holden central (Hh) and 

crater 1 (Hc1) materials exposed between dunes

Recent aeolian dunes, likely composed of chemically unaltered basaltic sand. At type 

locality, barchan to barchanoid dune form reflects limited sand supply and transport 

from north to south

Chaotic unit (Early Amazonian to Late Hesperian)—Discrete areas of severe structural disruption, resulting in dense fracturing, vertical movement, and some rotation of 

variably sized blocks. Less than 50% of original surface intact. Slope failures common on 

block margins. Type locality: Near head of Morava Valles at lat 15° S., long 26° W. 

(CTX P19_008509_1619_XN_18S025W)

Recent sand infilled some low areas between blocks. Displaced knobs 

and mesas composed of materials crosscut by chaotic unit. Crosscuts 

mountainous unit (Nm), terra unit (HNt), channel units (HNch1, 

HNch2), and basin fill 3 unit (Hb3)

Densely fractured, uplifted, and (or) partially collapsed surfaces due to localized 

inflation and (or) deflation of the surface in Late Hesperian to Early Amazonian. 

Topographic relations with fluvial surfaces suggest that uplift from volcanic 

intrusion, hydraulic pressure (less likely), or processes related to ground ice 

(unlikely) preceded and created space for subsequent collapse. Possible temporal and 

causal relation with weblike floor fractures in nearby impact basin and crater floors

Crater 2 unit (Late Amazonian to Late Hesperian)—Floor, rim, and continuous ejecta 

of morphologically fresh impact craters little modified by rim erosion and (or) infilling. 

Type locality: Unnamed crater at lat 18.5° S., long 29.3° W. 

(CTX P13_006281_1607_XN_19S029W)

Crater 1 unit (Late to Early Hesperian)—Rims of Holden and Ostrov craters and area 

thickly mantled by their ejecta. Type locality: Highlands east of Holden crater at lat 27° 

S., long 30.5° W. (CTX B05_011410_1534_XI_26S030W)

Age variable, but AHc2 locally overlies all other units but Ad

Somewhat more rugged texture than terra unit (HNt), which it overlies. 

Possibly coeval with base of etched unit (He). Underlies layered unit 

(Hl), fan units (Hf1, AHf2), and Holden central unit (Hh)

Interior materials, fractured rim, and continuous ejecta of Hesperian and Amazonian 

impact craters. Rocks emplaced or exposed by impact typically have older crystallization ages and reflect composition of target material

Moderately degraded crater rim and impact ejecta from Hesperian Holden and 

Ostrov craters

Terra unit (Early Hesperian to Late Noachian)—Widespread, smooth to rolling, 

cratered, and variably dissected surfaces between degraded impact craters. 

Type locality: East of Ostrov crater at lat 27o S., long 25.5o W. 

(CTX P18_008074_1536_XN_26S025W)

Mountainous unit (Middle Noachian)—Bedrock promontories including impact crater 

central peaks and mountain chains along impact basin rings. Mountains typically steep 

and variably eroded depending on age. Type locality: Holden impact basin inner ring at 

lat 22.2o S., long 32.75o W. (CTX B05_011687_1567_XI_23S032W)

Overlies mountainous unit (Nm). Underlies all other units

Oldest unit in map area

Noachian geomorphic surface resulting from impact cratering, ejecta emplacement, 

prolonged weathering, and erosion primarily by water and wind

Deeper Noachian bedrock outcrops exposed during impacts and overlain by terra 

unit

Fan 2 unit (Early Amazonian to Late Hesperian)—Sloping or cone-shaped deposits. 

Distributary paleochannel networks preserved in negative or (more commonly) positive 

relief. Type locality: Holden crater at lat 26.1° S., long 34.9° W. 

(CTX B04_011397_1534_XI_26S035W; HiRISE PSP_008193_1535)

Fan 1 unit (Late Hesperian)—Dark-toned, coarse-grained to bouldery, low-relief, 

multi-lobed deposit containing megaripples, subaqueous dunes, and crude bedding where 

exposed. Bedding commonly includes low-angle truncations near mouth of Uzboi Vallis, 

from which deposit was derived. More parallel and continuous bedding toward center of 

crater. Deposit locally entrains large clasts eroded from subjacent layered unit (Hl). 

Type locality: Holden crater floor at lat 26.6° S., long 34.5° W. 

(CTX B01_009841_1528_XI_27S034W, HiRISE PSP_002721_1530)

Holden central unit (Late Hesperian)—Moderately dark toned, low-thermal-inertia, 

smooth material surrounding etched or rugged outcrops of underlying rocks. Poor crater 

preservation and retention on both smooth surfaces and outcrops, but particularly on 

former. Type locality: Holden crater floor at lat 26.2° S., long 33.9° W. 

(CTX B06_011964_1544_XI_25S034W)

Layered unit (Late Hesperian)—Medium- to light-toned, phyllosilicate-bearing beds 

with meter to submeter thickness and lateral continuity to kilometers, overlain by 

dark-toned, more resistant capping layer that preserves small craters. Lower light-toned 

layers typically deeply eroded, exposed as scarps, and largely devoid of small craters 

where capping layer removed. Polygonal fractures observed in some beds. Type locality: 

Holden crater floor at lat 26.65° S., long 34.78° W. (figs. 12A, 13)

Etched unit (Early to Late Hesperian)—Erosionally resistant material on Holden 

crater, Eberswalde crater, and Uzboi Vallis floors exposed where aeolian deflation 

selectively removed layered unit (Hl). Varied outcrops of (moving upsection) widespread 

and unsorted bouldery deposits, polygonally fractured materials, light-toned layered 

deposits, elongated and locally sinuous gravel deposits, and sand sheets. Light-toned 

strata commonly thinly bedded and exposed as scarps beneath more resistant, darkertoned capping layers. Type locality: Eberswalde crater floor at lat 23.9° S., long 33.3° W. 

(fig. 12B; HiRISE ESP_012610_1560 and ESP_011542_1530)

Basin fill 3 unit (Early to Late Hesperian)—Plains-forming unit in Ladon impact basin 

with high thermal inertia and generally well preserved populations of small, superimposed impact craters. Type locality: Floor of Ladon impact basin at lat 18.75° S., long 

27.4o W. (CTX P20_008720_1610_XN_19S027W, HiRISE PSP_008720_1610)

Basin fill 2 unit (Early Hesperian to Late Nochian)—Relatively smooth, low-relief 

plains confined to impact crater and basin floors. Small superimposed craters commonly 

well preserved in surface layer, but some basin fill 2 surfaces with exposed underlying 

layers have etched appearance and relatively poor crater retention. Type locality: Floor of 

Ladon impact basin at lat 18.4° S., long 27.8° W. (figs. 9, 11)

Basin fill 1 unit (Early Hesperian to Late Noachian)—Prominent knobby outcrops 

embayed by friable, wind-eroded layered deposits. Aeolian infill material common in 

deflated surfaces and topographic lows. Type locality: Holden impact basin floor at lat 

25.8o S., long 32.3o W. (fig. 10) 

Channel 2 unit (Early Hesperian to Late Noachian)—Smooth floor of main outlet 

valley from Holden impact basin (part of Ladon Valles) and deepest channel of Morava 

Valles. Type locality: Ladon Valles floor at lat 22.1o S., long 28.65o W. 

(CTX P02_001890_1572_XN_22S028W) 

Channel 1 unit (Early Hesperian to Late Noachian)—Eroded surfaces related to early 

incision of Uzboi, Ladon, and Morava Valles. Streamlined outcrops of terra and mountainous units common. Type locality: Ladon Valles at lat 23.5o S., long 28.9o W. 

(fig. 2; CTX P15_006993_1576_XN_22S029W)

Cone-shaped deposits derived from deeply dissected impact crater 

walls coalesced into broad bajada along western wall of Holden crater 

and around entire circumference of Ostrov crater. In Eberswalde 

crater, coarse-grained, sinuous distributary paleochannels and deflated 

interchannel fines concentrated on west margin of crater in deposit 

with distal scarp. Overlies terra unit (HNt), crater 1 unit (Hc1), and 

crater floor deposits (He, Hl, HNb2). Youngest fluvial deposits in map 

area

Overlies light-toned strata of layered unit (Hl), but potentially coeval 

with Hl unit’s dark-toned capping layer. Potentially contemporary with 

Holden central unit (Hh)

Located primarily inside central ring structure of Holden crater. Some 

small outcrops of underlying materials emplaced during Holden crater 

impact (crater 1 unit, Hc1). Possibly contemporary with fan 1 unit 

(Hf1)

In Holden crater, light-toned beds include three members 

(undifferentiated at map scale, see fig. 13). Lower member: strongest 

phyllosilicate signature of the three, poorly expressed bedding, and 

darker tone. Middle member: brighter in tone but weakly expressed 

bedding. Upper member: most widespread exposure, well bedded, with 

higher albedo and weaker phyllosilicate signature than underlying 

members. In Holden crater, unit overlies etched unit (He) and crater 1 

unit (Hc1) and underlies fan units (Hf1, AHf2). In Ladon Valles, unit 

overlies channel materials (HNch1, HNch2)

Small size of varied outcrops prohibits subdivision at map scale. Basal 

materials of etched unit possibly coeval with crater 1 unit (Hc1). 

Smaller outcrops higher in section possibly coeval with layered unit 

(Hl) and fan 2 unit (AHf2). Underlies Holden central unit (Hh) and fan 

1 unit (Hf1)

At type locality, unit overlies and embays moderately indurated, etched 

deposits and subjacent layered deposits composed of or weathering into 

boulders (HNb2)

Unit may include materials contemporary with channel units (HNch1, 

HNch2). Overlies basin fill 1 unit (HNb1) and terra unit (HNt). 

Underlies basin fill 3 unit (HNb3) and fan 2 unit (AHf2) 

Where exposed, some layered deposits between knobs resemble basin 

fill 2 (HNb2) unit. Overlies terra unit (HNt) and underlies basin fill 2 

unit (HNb2) 

Overlies terra unit (HNt). Contemporary with channel 1 unit (HNch1). 

Locally buried by light-toned deposits (Hl)

Overlies terra unit (HNt). Contemporary with channel 2 unit (HNch2)

Late Hesperian to Early Amazonian alluvial deposits composed primarily of gravel 

and fines, emplaced by fluvial sediment transport with little to no evident contribution from debris flows. Low abundance of boulders visible at HiRISE scale at type 

locality. Relief inversion of distributary paleochannels due to selective aeolian 

erosion of granule- to sand-sized material originally deposited between channels. In 

Eberswalde crater, similar material composition to Holden crater fans deposited in 

lower-energy deltaic environment. Separate lobes of Eberswalde deposit indicate 

multiple water levels, and lateral migration of paleochannels that formed meander 

loops and cutoffs suggests periods of base-level stability during aggradation

High-energy flood deposit, composed of chemically unaltered to weakly altered 

plateau and highland units bedrock (HNt, Nm), deposited when Hesperian paleolake 

impounded in Uzboi Vallis overflowed and breached Holden crater rim

Hesperian sedimentary deposit, subsequently etched by wind and mostly mantled by 

recent aeolian sand sheet

Hesperian fine-grained, phyllosilicate-bearing, lacustrine and (or) distal alluvial 

deposits overlain by coarse-grained alluvial sediments and (or) indurated aeolian 

sand sheets of likely basaltic mineralogy. Capping layer possibly coeval with and 

laterally equivalent to fan 1 unit (Hf1), particularly near entrance breach of Uzboi 

Vallis, but typically thinner and finer grained

Deflated crater-fill deposits overlying Hesperian Holden crater ejecta or crater fill. 

Includes fine-grained, phyllosilicate-bearing, lacustrine and (or) distal alluvial 

deposits overlain by coarse-grained alluvial sediments (stripped over much of area) 

and recent aeolian sand sheets of likely basaltic mineralogy. Megabreccia and 

possible impact melt appear related to Holden crater impact, and unit may include 

early, coarse-grained sedimentary deposits

Late Noachian to Early Hesperian deposits composed of resistant indurated 

sediments and (or) thin lava flows 

Moderately to strongly indurated alluvial, volcanic, or aeolian fill materials; origin 

and composition may vary within and between individual basins. Type locality 

interpreted as underlying flood deposits from Ladon Valles, medium- to light-toned 

sedimentary deposits associated with later infilling, and darker-toned capping layer

Knobby outcrops of Hesperian Holden crater ejecta and older channel deposits with 

interspersed sedimentary deposits and recent aeolian infill. Development of knobby 

texture postdates Holden impact

Surfaces deeply eroded by Late Noachian to Early Hesperian catastrophic flooding 

and veneered by coarse fluvial sediments during waning flow

Surfaces eroded by Late Noachian to Early Hesperian catastrophic flooding and 

thinly veneered by coarse fluvial sediments during waning flow

Unit Unit name, age, description, and type locality

label

Additional characteristics Interpretation

DESCRIPTION OF MAP UNITS

SURFICIAL DEPOSITS

CRATER UNITS

SEVERELY DEFORMED UNITS

Contact—Dashed where approximately located

Normal fault—On map, line follows center of fracture or 

graben. On cross section, arrows show relative movement

Reverse fault—Line follows crest of wrinkle ridge

Chain of secondary craters—Approximately located

Small valley—Line follows valley thalweg

BASIN, CRATER, AND CHANNEL-FILL UNITS

PLATEAU AND HIGHLAND UNITS

EXPLANATION OF MAP SYMBOLS

Small entrenched channel—Line follows channel thalweg

Fresh crater rim crest (class C1)—Hatchures point into crater

Degraded crater rim crest (classes C2 and C3)—Current 

location reflects rim retreat during crater degradation

Impact basin ring

Figure location and number

[Unit descriptions and interpretations based on morphology, albedo, brightness temperature, stratigraphic position, 

and superimposed crater populations as seen in available orbital imaging and topography. These data include Mars 

Odyssey Thermal Emission Imaging System (THEMIS, infrared and visible), Mars Global Surveyor (MGS) Mars 

Orbiter Camera (MOC, narrow-angle), Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science 

Experiment (HiRISE) and Context (CTX) cameras, and 128-pixel/degree MGS Mars Orbiter Laser Altimeter 

(MOLA) Mission Experiment Gridded Data Record (MEGDR). Derived products from MRO Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) used, where available, to identify mineralogical differences 

within and between mapped geologic units. See pamphlet for details and references]

Ad

AHc2

Hc1

AHct

AHf2

Hf1

Hh

Hl

He

Hb3

HNb2

HNb1

HNch2

HNch1

HNt

Nm

Any use of trade, product, or firm names in this publication is for descriptive purposes only 

and does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, 

CO 80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3209/

Suggested citation: Irwin, R.P., III, and Grant, J.A., 2013, Geologic map of the MTM –15027, 

–20027, –25027, and –25032 quadrangles, Margaritifer Terra Region of Mars: U.S. Geological 

Survey Scientific Investigations Map 3209, scale 1:1,000,000, http://pubs.usgs.gov/sim/3209/. Printed on recycled paper

Geologic Map of the MTM –15027, –20027, –25027, and –25032 Quadrangles,

Margaritifer Terra Region of Mars

By

Rossman P. Irwin, III1, and John A. Grant1

2013

Prepared on behalf of the Planetary Geology and Geophysics Program, 

Solar System Exploration Division, Office of Space Science, National 

Aeronautics and Space Administration

Edited by J.L. Zigler; cartography by Darlene A. Ryan and Kathryn Nimz

Manuscript approved for publication December 9, 2011

Descriptions of nomenclature used on map are listed at 

http://planetarynames.wr.usgs.gov/

Prepared for the

National Aeronautics and Space Administration

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3209

Pamphlet accompanies map

20 0 20 40 60 80 100

SCALE 1:1 004 000 (1 mm = 1.004 km ) AT 350° LONGITUDE

TRANSVERSE MERCATOR PROJECTION

KILOMETERS

Planetocentric latitude and east longitude coordinate system shown in black.

Planetographic latitude and west longitude coordinate system shown in red.

1

Center for Earth and Planetary Studies, Smithsonian Institution

500

METERS

–500

–1000

–1500

–2000

–2500

–3000

–3500

–4000

500

0

METERS

ELEVATION ELEVATION

–500

–1000

–1500

–2000

–2500

–3000

–3500

–4000

0 100 200 300 400 500

DISTANCE (KILOMETERS)

600 700 800 900 1000

0

A A ́

Holden

crater

Holden impact basin Ladon

Valles

Ladon impact basin

AHct

HNb2

Nm

HNb2

HNt

HNt

HNt

HNb1

Hc1

HNt

Hc1

Possible magmatic intrusions

VERTICAL SCALE GREATLY EXAGGERATED x 87

Possible magmatic intrusions

HNb2

Hl Hl

Hf1 Hh

Hh Ad

HNch2

SCHEMATIC CROSS SECTION

[Not to map scale. Subsurface contacts are conceptual; unit thicknesses are unknown]

Figure 4. Hartmann (2005) isochron plot for all fresh and degraded craters in map area, except for Ladon and 

Holden impact basins. Crater count indicates resurfacing about Middle to Late Noachian boundary and ongoing 

crater degradation into Early Hesperian.

16 31 63 125 250 500 1

(km)

2 4 8 16 32 64 128 256

102

101

100

10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8

Number of Craters/km2

Rbolide = 2.6, Schmidt-Housen scaling 2004 Iteration 04-01-19

10,000 yr

100,000 yr

1 Ma

10 Ma

100 Ma

1 Ga

3 Ga

3.5 Ga

4 Ga

(m)

Diameter

Figure 5. Hartmann (2005) isochron plot for fresh craters superimposed on terra unit. Crater count indicates 

Early Hesperian age for waning of crater degradation in map area. 

16 31 63 125 250 500 1

(km)

2 4 8 16 32 64 128 256

102

101

100

10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8

Number of Craters/km2

Rbolide = 2.6, Schmidt-Housen scaling 2004 Iteration 04-01-19

10,000 yr

100,000 yr

1 Ma

10 Ma

100 Ma

1 Ga

3 Ga

3.5 Ga

4 Ga

(m)

Diameter

16 31 63 125 250 500 1

(km)

2 4 8 16 32 64 128 256

102

101

100

10-1

10-2

10-3

10-4

10-5

10-6

10-7

10-8

Number of Craters/km2

Rbolide = 2.6, Schmidt-Housen scaling 2004 Iteration 04-01-19

10,000 yr

100,000 yr

1 Ma

10 Ma

100 Ma

1 Ga

3 Ga

3.5 Ga

4 Ga

(m)

Diameter

Figure 6. Hartmann (2005) isochron plot for craters superimposed on crater 1 unit (AHc1) surrounding Holden 

crater. Crater count indicates a Hesperian age for Holden impact.

Figure 7. Enlarged image of etched unit (He) 

in floor of Uzboi Vallis southwest of Holden 

crater. Near top of image, darker-toned 

material overlies medium-toned stratified 

(layered) and lighter-toned fractured materials. 

Toward bottom of image, lighter-toned 

fractured materials are exposed on valley 

floor. Patchy, darker-toned aeolian bedforms 

and sand sheets partially cover these outcrops; 

otherwise, stratigraphy is exposed downsection from north to south. Subset of HiRISE 

ESP_011608_1525, centered at lat 27.1° S., 

long 35.2° W. See map for image location.

aeolian bedforms (valley floor)

aeolian bedforms

fractured

fractured

fractured

layered

0 100 200 300 400 500 METERS

0 5 10 15 20 25 KILOMETERS

fan 2

unit AHf2

crater 1 

unit Hc1

etched

unit He

gullies

layered unit

breach

fan 1

unit Hf1

fan 2

unit AHf2

etched

unit He

Figure 8. Enlarged image of overflowed rim and breach where Uzboi Vallis enters 

Holden crater. Gullies in west side of image formed when a lake in Uzboi Vallis 

overtopped the crater rim. Flow coalesced into a single breach and formed lobate fan 1 

unit (Hf1) deposits in upper right. Mosaic of THEMIS visible imaging at 18 m/pixel, 

centered at lat 26.8° S., long 325.2° E. See map for image location.

Figure 9. Enlarged image of basin fill 2 

unit (HNb2), showing stratified outcrop 

exposed in graben on floor of Ladon 

impact basin. Dark-toned capping 

material preserves a population of small 

craters and disaggregates into boulders. 

Medium-toned, stratified to crudely 

stratified (layered), apparently finergrained materials underlie it. Recent 

aeolian bedforms cover the floor of the 

graben at the top of the image; otherwise, the stratigraphy is exposed 

down-section from south to north. 

Subset of HiRISE ESP_013045_1615, 

centered at lat 18.4° S., long 27.8° W. 

See map for image location.

aeolian bedforms

layered

capping material

massive to

crudely layered

0 100 200 300 400 500 METERS

Figure 10. Enlarged image of basin 

fill 1 unit (HNb1), showing 

dark-toned capping material and 

medium-toned, wind-eroded 

materials exposed on floor of 

Holden impact basin, just east of 

Holden crater. Recent aeolian 

bedforms occupy corridors 

between knobs of capping material. 

Subset of HiRISE 

PSP_010197_1540, centered at lat 

25.8° S., long 32.3° W. See map for 

image location.

capping material

capping

material

etched material and

aeolian bedforms

0 100 200 300 400 500 METERS

capping material

capping material

deflated capping material

etched

B

0 100 200 300 400 500 METERS

capping material

aeolian

bedforms

etched

Figure 11. Enlarged image of basin fill 2 unit (HNb2), showing erosional expression 

of stratigraphy shown in figure 9. See map for image locations. A. Stratigraphic 

section exposed downsection from north to south, including dark-toned capping 

material and weakly resistant, medium- to lighter-toned materials (etched surface). 

Subset of HiRISE ESP_013045_1615, located south of figure 9. B. Closeup of 

outcrops similar to A moving downsection from south to north. Subset of HiRISE 

ESP_015946_1620, centered at lat 17.9° S., long 332.6° E. Compare to stratigraphy 

exposed in Holden impact basin to the south (fig. 10).

A

0 100 200 300 400 500 METERS

capping material

layered

capping

material

layered

layered

capping

A

0 100 200 300 400 500 METERS

capping material

layered

aeolian

bedforms

blocky

material

B

0 100 200 300 400 500 METERS

capping material

 aeolian bedforms

aeolian bedforms

layered

C

0 100 200 300 400 500 METERS

Figure 12. Images comparing light-toned, layered deposits (LTLDs) in map area. See map for image locations. A. Layered unit (Hl), showing LTLDs and dark-toned capping materials 

exposed on floor of Holden crater. Four stratal packages are exposed in outcrop in right half of image. Stratification is laterally continuous through scene. Subset of HiRISE 

ESP_016276_1535, centered at lat 26.4° S., long 34.8° W. B. Fan 2 unit (AHf2) at north margin of Eberswalde delta, showing dark-toned alluvial capping material, lighter-toned subjacent 

strata (layered), and blocky material exposed to north, moving downsection from south to north. HiRISE PSP_001336_1560, centered at lat 23.8° S., long 33.6° W. C. Layered unit (Hl), 

showing darker-toned capping material and LTLDs in Ladon Valles, moving downsection from north to south. HiRISE PSP_006637_1590, centered at lat 20.9° S., long 29.7° W.

Figure 13. Enlarged image of layered unit (Hl) in Holden crater, showing dark-toned 

capping material and LTLDs exposed in three members moving downsection from north 

to south. Lower member has strongest phyllosilicate signature, poorly expressed stratification, and darker tone. Middle member is brighter in tone but also has weakly expressed 

stratification. Upper member has most widespread exposure, is well-stratified, and has 

higher albedo and weaker phyllosilicate signature than underlying members. HiRISE 

PSP_002088_1530, centered at lat 26.6° S., long 34.8° W. See map for image location.

capping material

layered

upper member

middle member

lower member and

aeolian bedforms

0 100 200 300 400 500 METERS

Figure 14. Enlarged image showing deeply eroded interior wall and 

alluvial fans in Ostrov crater. Mosaic of THEMIS DIR imaging at 100 

m/pixel, centered at lat 26.5o S., long 331.9o E. See map for image 

location.

0 100 200 300 400 500 KILOMETERS

Figure 15. Enlarged image of fan 2 unit (AHf2), 

showing stratigraphy exposed in an inverted 

paleochannel of Eberswalde crater delta, moving 

downsection from north to south. HiRISE 

PSP_001534_1560, centered at lat 23.8° S., long 

33.6° W. See map for image location.

0 100 200 300 400 500 METERS

3,000

Elevation,

in meters

2,700

2,400

2,100

1,800

1,500

1,200

900

600

300

0

–300

–600

–900

–1,200

–1,500

–1,800

–2,100

–2,400

Valles Marineris Margaritifer

Chaos

Nirgal Vallis

Uzboi Vallis

Ladon

Valles

Samara Valles

Morava

Loire Valles

Valles

Bond

Holden

Ladon

basin

Ostrov Holden basin

Hale

Argyre basin

–15027

–25032 –25027

–20027

MARGARITIFER

TERRA

Figure 1. Regional context of four MTM quadrangles in map area, showing labeled major 

craters, impact basins, and valleys. Base image is THEMIS daytime infrared (DIR) mosaic 2.0 

with gores filled by Viking Orbiter Mars Digital Image Mosaic (MDIM) 2.1, colored with Mars 

Orbiter Laser Altimeter (MOLA) Mission Experiment Gridded Data Record (MEGDR) topography at 128 pixels/degree. Projection is simple cylindrical.

0°

45°W 15°W

40°S

MC–19

MC–3

MC–4 MC–5

MC–6

MC–10 MC–11 MC–12 MC–13

MC–1

MC–18 MC–20 MC–21

MC–25

MC–26 MC–27

MC–28

MC–30

QUADRANGLE LOCATION

Photomosaic showing location of map area. An outline of 

1:5,000,000-scale quadrangles is provided for reference.

300°

300°

60°

60°

0°

30°

65°

270° 315° 0° 45° 90°

–30°

–65°

0°

30°

65°

–30°

–65°

Figure 3. THEMIS nighttime infrared 2.0 mosaic of map area 

(256 pixels/degree), transverse Mercator projection, planetographic latitude and longitude coordinate system.

13°S

14°S

15°S

16°S

17°S

18°S

19°S

20°S

21°S

22°S

35°W 34°W 33°W 32°W 31°W

30°W 29°W 28°W 27°W 26°W 25°W

23°S

24S°

25°S

26°S

27°S

28°S

Figure 2. Base mosaic of THEMIS DIR images of map area at 

100 m/pixel resolution, transverse Mercator projection, planetographic latitude and longitude coordinate system.

13°S

14°S

15°S

16°S

17°S

18°S

19°S

20°S

21°S

22°S

35°W 34°W 33°W 32°W 31°W

30°W 29°W 28°W 27°W 26°W 25°W

23°S

24°S

25°S

26°S

27°S

28°S